UPD17073 NEC, UPD17073 Datasheet - Page 147

• Manufacturer Part Number: UPD17073
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
• Manufacturer: NEC

16.3 Start Control Block and IF Counter
16.3.1 Configuration of start control block and IF counter
by an internal gate signal. Although this frequency is counted as is in the AMIF count mode, it is halved and then
counted in the FMIF count mode.
Figure 16-4 shows the configuration of the start control block and IF counter.
The start control block starts counting of the frequency counter and detects the end of counting.
The counter is started by the IF counter control register.
The end of counting is detected by the IF counter gate status detection register.
Figure 16-5 shows the configuration and function of the IF counter control register.
Figure 16-6 shows the configuration and function of the IF counter gate status detection register.
The 16.3.2, describe the gate operations when the IF counter function is selected.
The IF counter is a 16-bit binary counter that counts up the input frequency when the IF counter function is selected.
When the IF counter function is used, the IF counter counts the frequency input to the pin while the gate is opened
The IF counter is cleared to 0000H when its count value has reached FFFFH, and then continues counting.
The count value is read via data buffer by the IF counter data register (IFC).
The count value is reset by the IF counter control register.
Figure 16-7 shows the configuration and function of the IF counter data register.
From gate
time selector
block
Figure 16-4. Configuration of Start Control Block and IF Counter
Gate signal
IFCG flag
Start control
IFCSTRT flag
IFCRES flag
RES
IF counter data
register (IFC)
IF counter
(16 bits)
DBF
16
16
PD17072,17073
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